Antenna



' 930.1 A. MEISSN4E4R 83,

ANTENNA Filed June 17; 1925 T H 2 I fig. 5

avwwwoz ALEXANDER MEISSNER Patented Nov. 25, 1930 UNITED STATESPATEINTOFFICE ALEXANDER EIsSNER, on BERLIN, GERMANY, Assienon rooEsn'LLscHArr. run DRAI-ITLOSE TELEGRAPHIE M. B. H. HALLEsonns, BERLIGERMANY, A CORPORA' TION on GERMANY ANTENNA Application filed June 17,1925, Serial No. 37,82G, and in Germany July 25, 1924.

One object of the invention is the provision of an antenna suitable fortransmitting or receiving short wave lengths.

Another object of the invention is the proprovision of an antennasuitable for short wave lengths and having loading devices 1nse-rtedtherein in symmetrical relationship with the current distribution undershort wave operation. j

The invention is illustrated in the accompanying drawing in which Figure1 shows a three-quarter wave antenna for radiating short waves;

Figure 2 represents a similar antenna inductively loaded;

Figure 3 shows capacitive loading;

Figure 4 indicates a combination of inductive and capacitive loading;and

Figure 5 shows the vertical portion of the conductor leading to aquarter wave antenna a "plurality of half waves in length.

It is well-known that for the purposes of intelligence transmission bymeans of short electrical waves so-called space-radiation antennaehavebeen used. These antennae asa rule consist of a rectilinear wire whichis excited to oscillate at three-quarter wave length or a Whole multipleof a half wave length plus one quarter wave length. In Fig: 1 such astraight oscillator is shown jointly with the 9 curve showing thecurrent distribution when excited at three quarter wave length. The partof the antenna between points A and B gives the proportion of the spacerad1at1on, while the current of part BC contributes more to theproduction of surface waves. It is a well known fact that operation onshort waves is more desirable at certain times of the day than atothers, so that there arises the neces sity to work on longer wavelengths durlng certain portions of the day. Now, the present inventionprovides a simple arrangeirient adapted to change to long wave operationwhile using the same antenna tower or mast and the same antenna wire.This isaccom plished by the insertion of wave extension means such ascoils, larger condensers, as well as' combinationsoi' coils andcapacitiveresistances which of courseis well knowninit: self. Now,according to theinvention these extension-means are inserted or.connected ,in

the antenna wireand are positioned'in a symg metrical manner withreference to the current loops of the short working waves. For

instance, in the case of a space-radiation ang tenna which iseXcitedinjthe manner illus trated in Fig. 1, the coil must be insertedin the middle o-f portion AB, as-depicted in Fig. A

2.. Also a condenser: (shown by the broken lines in the figure) could beconnected with the antenna coil mentioned in ordeinthat the desiredextension may be obtained. Another form of construction according to theinvent1on is illustrated in Fig. 3. Accordinggto the latter, at bothends of the section AB enlarged capacity surfaces by the addition of fanlike disposed Wires are provided. In the form of construction of Fig. 4,horizontal capacity surfaces are used at A and B. Fig. 5 illustrates theuse and application of the idea 'underlylng the invention to the case inwhich the antenna radiates at a short Wave andin which the longitudinaldimensions of the antenna wire correspond to one quarter wave length. a

The advantage which the invention offers, as can be readily seen fromthe examples here cited, consists in that one and the same mast or toweris employed for-the antenna working on short waves and longer waves, andin that the antenna wire for short waves is adapted in the simplestpossible way to the transmis corresponds to a short wave length to asubstantially longer wave length.

In the claims which follow I shall use the term loop to mean a half ofan electrical 5 wave. Thus, the threequarter Wave antennae in Figures 1through 4 contain one and onehalf loops Having described my invention, Iclaim: 1. The method of changing the wave length of a space radiationantenna, the cur rent distribution of which has an odd number of halfloops and includes at least an entire current loop, which comprises thestep of loading the antenna symmetrically with respect to the currentloop.

2. A space radiation antenna comprising a conductor the currentdistribution in which contains a whole and a half current loop, andreactance devices located symmetrically with respect to the wholecurrent loop.

3. The combination with an antenna having a current distribution wherebythere are a plurality of current nodes, and at one end a current anti-node, of loading devices located symmetrically with respect to a pair ofadjacent current nodes.

4. An antenna structure for use with either short or long wavescomprising a grounded linear oscillator the length of which is an oddnumber of fourths of the short Wave length,

and having for use with the longer Wave loading devices locatedsymmetrically with respect to the current distribution existing duringshort Wave operation.

ALEXANDER MEISSNER.

